Touchpad Buttons Won't Deactivate with Synaptics Driver

* Linux Mint 21.1 (Cinnamon)
* Linux Kernel 5.15.0-56-generic
* Cinnamon version 5.6.5
  - I am not using daily builds
* 64-bit
* Dell Latitude E6440
* Intel Core i7-4610M CPU
* 16GB RAM
* Intel HD Graphics 4600

Issue Description

After installing the Synaptics touchpad driver, disabling the touchpad doesn't result in the physical touchpad buttons becoming disabled. Therefore, pressing the touchpad buttons still results in mouse clicks even though the touchpad can no longer move the mouse pointer.

Steps to Reproduce

• Install the Synaptics touchpad driver using the following terminal command:
  sudo apt install xserver-xorg-input-synaptics
• Restart your computer to ensure the drivers take effect.
• Confirm the drivers are active using the following terminal command:
  grep -i "Using input driver" /var/log/Xorg.0.log
• Disable the touchpad using any available mechanism, including:
  • Pressing the keyboard shortcut (Fn+F5 on my computer)
  • Using the Mint GUI (Mouse and Touchpad -> Touchpad -> Touchpad is: Disabled)
• Press the physical touchpad buttons.

Expected Behaviour

The physical touchpad buttons stop functioning when the touchpad is disabled.

Actual Behaviour

The physical touchpad buttons continue to function when the touchpad is disabled.

Reproducibility

100% consistent

Other Information

syslog.txt
xsession-errors.txt

Start with Cinnamon's touchpad-disable path and its interaction with the Synaptics driver, following the reproduction steps and attached syslog and xsession-errors files. Confirm that disabling the touchpad also suppresses clicks from its physical buttons, then verify the behavior through the keyboard shortcut and Mint GUI.